Systems and methods for synchronized three-dimensional laser incisions

ABSTRACT

Embodiments of this invention generally relate to ophthalmic laser procedures and, more particularly, to systems and methods for creating synchronized three-dimensional laser incisions. In an embodiment, an ophthalmic surgical laser system comprises a laser delivery system for delivering a pulsed laser beam to a target in a subject&#39;s eye, an XY-scan device to deflect the pulsed laser beam, a Z-scan device to modify a depth of a focus of the pulsed laser beam, and a controller configured to synchronize an oscillation of the XY-scan device and an oscillation of the Z-device to form an angled three-dimensional laser tissue dissection.

This application is a non-provisional application and claims the benefitunder 35 U.S.C. §119(e) of U.S. Provisional Patent Application No.62/048,118, filed Sep. 9, 2014, the full disclosures of all of which areincorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of this invention generally relate to laser-assistedophthalmic procedures, and more particularly, to systems and methods forsynchronized three-dimensional laser incisions.

BACKGROUND

Eye surgery is now commonplace with some patients pursuing it as anelective procedure to avoid using contact lenses or glasses to correctmyopia, hyperopia, and astigmatism, and others pursuing it to correctadverse conditions such as cataracts. Moreover, with recent developmentsin laser technology, laser surgery is becoming the technique of choicefor ophthalmic procedures. Indeed, some surgeons prefer a surgical laserbeam over manual tools like microkeratomes and forceps, because thelaser beam can be focused precisely on extremely small amounts of oculartissue, thereby enhancing accuracy and reliability of the procedure.

Typically, different laser eye surgical systems use different types oflaser beams for the various procedures and indications. These include,for instance, ultraviolet lasers, infrared lasers, and near-infrared,ultra-short pulsed lasers.

For example, in the commonly-known LASIK (Laser Assisted In SituKeratomileusis) procedure, an ultra-short pulsed laser is used to cut acorneal flap to expose the corneal stroma for photoablation withultraviolet beams from an excimer laser. Ultra-short pulsed lasers emitradiation with pulse durations as short as 10 femtoseconds and as longas 3 nanoseconds, and a wavelength between 300 nm and 3000 nm.

Besides cutting corneal flaps, surgeons use ultra-short pulsed lasers toperform cataract-related procedures, including creating cataract entryincisions, capsulotomies, as well as fragmenting and softening thecataractous lens prior to enable easier removal. They also use them tocreate relaxing incisions in the cornea to correct a patient'sastigmatism. Examples of laser systems that provide ultra-short pulsedlaser beams include the Abbott Medical Optics iFS Advanced FemtosecondLaser, the IntraLase FS Laser, and the Catalys Precision Laser System.

The ability to produce an angled side cut is a highly desired feature inultra-short pulsed surgical systems used for cutting corneal flaps. Thisis because the angled side cut enables proper repositioning of thecorneal flap after the corneal bed has been ablated with the excimerlaser's ultraviolet beams. Proper repositioning of the flap in turnimproves the flap edge's regrowth and healing.

Known methods for creating an angled side cut, such as those used in theAbbott Medical Optics iFS system and other conventional ultra-shortpulsed laser systems, involve X-Y galvanometers (or “galvos”) scanningthe laser focus to produce a series of rings of different diameterswhile the Z-scanner of the system moves slowly vertically. While thesemethods are suitable for lasers with pulse repetition rates (commonlyreferred to as “rep-rate”) in the hundred KHz range and beam deliveryoptics covering the entire field of view for corneal flap cutting, theyare not optimum for other ophthalmic surgical laser designs that do notmeet these characteristics.

Hence, improved systems and methods are needed for making an angled sidecut for corneal flap creation during laser ophthalmic surgery.

SUMMARY OF THE INVENTION

Accordingly, this disclosure provides systems and methods forsynchronized three-dimensional laser incisions for use in suitableophthalmic laser surgery systems so as to obviate one or more problemsdue to limitations and disadvantages of the related art. In oneembodiment, an ophthalmic surgical laser system includes a laserdelivery system for delivering a pulsed laser beam to a target in asubject's eye, an XY-scan device to deflect the pulsed laser beam, aZ-scan device to modify a depth of a focus of the pulsed laser beam, anda controller configured to synchronize an oscillation of the XY-scandevice and an oscillation of the Z-device to form an angledthree-dimensional laser tissue dissection. The ophthalmic surgical lasersystem can form angled three-dimensional laser tissue dissection in anyshape using mathematical relation to synchronize the oscillation of theXY-scan device and the oscillation of the Z-device. The ophthalmicsurgical laser system is configured to also perform error management andmaintain the synchronization of the oscillation of the XY-scan deviceand the oscillation of the Z-device throughout the procedure. In anotherembodiment, the ophthalmic surgical laser system also removes tissueduring the same procedure. In yet another embodiment, the surgical lasersystem can be used for non-ophthalmic procedures. In a furtherembodiment, the laser system can be used for processing non-organicmaterials, such as for micromachining.

This summary and the following detailed description are merelyexemplary, illustrative, and explanatory, and are not intended to limit,but to provide further explanation of the invention as claimed.Additional features and advantages of the invention will be set forth inthe descriptions that follow, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription, claims and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages will be facilitated by referring to the following detaileddescription that sets forth illustrative embodiments using principles ofthe invention, as well as to the accompanying drawings, in which likenumerals refer to like parts throughout the different views. Like parts,however, do not always have like reference numerals. Further, thedrawings are not drawn to scale, and emphasis has instead been placed onillustrating the principles of the invention. All illustrations areintended to convey concepts, where relative sizes, shapes, and otherdetailed attributes may be illustrated schematically rather thandepicted literally or precisely.

FIG. 1 is a perspective view of a surgical ophthalmic laser systemaccording to an embodiment of the present invention.

FIG. 2 is another perspective view of a surgical ophthalmic laser systemaccording to an embodiment of the present invention.

FIG. 3 is a simplified diagram of a controller of a surgical ophthalmiclaser system according to an embodiment of the present invention.

FIG. 4 illustrates a synchronization of an XY-scanner and a Z-scanner ofa surgical ophthalmic laser system according to an embodiment of thepresent invention.

FIGS. 5A and 5B show exemplary cross-sections of side cuts of a surgicalophthalmic laser system according to an embodiment of the presentinvention.

FIGS. 6A and 6B show other exemplary cross-sections of side cuts of asurgical ophthalmic laser system according to an embodiment of thepresent invention.

FIGS. 7A to 7D show simulated examples of side cuts of a surgicalophthalmic laser system according to an embodiment of the presentinvention.

FIG. 8 is a flowchart illustrating a process according to an embodimentof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of this invention are generally directed to systems andmethods for laser-assisted ophthalmic procedures, and more particularly,to systems and methods for synchronized three-dimensional laserincisions. In one embodiment, the system has a femtosecondoscillator-based laser operating at a repetition rate in the MHz range,for example, 10 MHz or higher, and produces an angled side cut forcutting a corneal flap.

Referring to the drawings, FIG. 1 shows a system 10 for making anincision in a material 12. The system 10 includes, but is not limitedto, a laser 14 capable of generating a pulsed laser beam 18, an energycontrol module 16 for varying the pulse energy of the pulsed laser beam18, a Z-scanner 20 for modifying the depth of the pulse laser beam 18, acontroller 22, a prism 23 (e.g., a Dove or Pechan prism, or the like),and an XY-scanner 28 for deflecting or directing the pulsed laser beam18 from the laser 14 on or within the material 12. The controller 22,such as a processor operating suitable control software, is operativelycoupled with the Z-scanner 20, the XY-scanner 28, and the energy controlunit 16 to direct a scan line 30 of the pulsed laser beam along a scanpattern on or in the material 12. In this embodiment, the system 10further includes a beam splitter 26 and a detector 24 coupled to thecontroller 22 for a feedback control mechanism (not shown) of the pulsedlaser beam 18. Other feedback methods may also be used, including butnot necessarily limited to position encoder on the scanner 20 or thelike. In one embodiment, the pattern of pulses may be summarized inmachine-readable data of tangible storage media in the form of atreatment table. The treatment table may be adjusted according tofeedback input into the controller 22 from an automated image analysissystem in response to feedback data provided from an ablation monitoringsystem feedback system (not shown). Optionally, the feedback may bemanually entered into the controller 22 by a system operator. Thefeedback may also be provided by integrating a wavefront measurementsystem (not shown) with the laser surgery system 10. The controller 22may continue and/or terminate a sculpting in response to the feedback,and may also modify the planned sculpting based at least in part on thefeedback. Measurement systems are further described in U.S. Pat. No.6,315,413, the entire disclosure of which is incorporated herein byreference.

In an embodiment, the system 10 uses a pair of scanning mirrors or otheroptics (not shown) to angularly deflect and scan the pulsed laser beam18. For example, scanning mirrors driven by galvanometers may beemployed where each of the mirrors scans the pulsed laser beam 18 alongone of two orthogonal axes. A focusing objective (not shown),—whetherone lens or several lenses—, images the pulsed laser beam 18 onto afocal plane of the system 10. The focal point of the pulsed laser beam18 may thus be scanned in two dimensions (e.g., the x-axis and they-axis) within the focal plane of the system 10. Scanning along thethird dimension, i.e., moving the focal plane along an optical axis(e.g., the z-axis), may be achieved by moving the focusing objective, orone or more lenses within the focusing objective, along the opticalaxis.

Laser 14 may comprise a femtosecond laser capable of providing pulsedlaser beams, which may be used in optical procedures, such as localizedphotodisruption (e.g., laser induced optical breakdown). Localizedphotodisruptions can be placed at or below the surface of the materialto produce high-precision material processing. For example, amicro-optics scanning system may be used to scan the pulsed laser beamto produce an incision in the material, create a flap of material,create a pocket within the material, form removable structures of thematerial, and the like. The term “scan” or “scanning” refers to themovement of the focal point of the pulsed laser beam along a desiredpath or in a desired pattern.

Although the laser system 10 may be used to photoalter a variety ofmaterials (e.g., organic, inorganic, or a combination thereof), thelaser system 10 is suitable for ophthalmic applications in someembodiments. In these cases, the focusing optics direct the pulsed laserbeam 18 toward an eye (for example, onto or into a cornea) for plasmamediated (for example, non-UV) photoablation of superficial tissue, orinto the stroma of the cornea for intrastromal photodisruption oftissue. In these embodiments, the surgical laser system 10 may alsoinclude a lens to change the shape (for example, flatten or curve) ofthe cornea prior to scanning the pulsed laser beam 18 toward the eye.The laser system 10 is capable of generating the pulsed laser beam 18with physical characteristics similar to those of the laser beamsgenerated by the laser systems disclosed in U.S. Pat. No. 4,764,930,U.S. Pat. No. 5,993,438, and U.S. patent application Ser. No.12/987,069, filed Jan. 7, 2011, the entire disclosures of which areincorporated herein by reference.

FIG. 2 shows another exemplary diagram of the system 10. FIG. 2 shows amoveable XY-scanner (or XY-stage) 28 of a miniaturized femtosecond lasersystem. In this embodiment, the system 10 uses a femtosecond oscillatoror a fiber oscillator-based low energy laser. This allows the laser tobe made much smaller. The laser-tissue interaction is in thelow-density-plasma mode. An exemplary set of laser parameters for suchlasers include pulse energy in the 50-100 nJ range and pulse repetitiverates (or “rep rates”) in the 5-20 MHz range. A fast-Z scanner 20 and aresonant scanner 21 direct the laser beam 18 to the prism 23. When usedin an ophthalmic procedure, the system 10 also includes a patientinterface 31 design that has a fixed cone nose and a portion thatengages with the patient's eye. A beam splitter is placed inside thecone of the patient interface to allow the whole eye to be imaged viavisualization optics. In one embodiment, the system 10 uses: optics witha 0.6 numerical aperture (NA) which would produce 1.1 μm Full Width atHalf Maximum (FWHM) focus spot size; and a resonant scanner 21 thatproduces 1-2 mm scan line with the XY-scanner scanning the resonant scanline to a 10 mm field. The prism 23 rotates the resonant scan line inany direction on the XY plane. The fast-Z scanner 20 sets the incisiondepth and produces a side cut. The system 10 may also include an auto-Zmodule 32 to provide depth reference. It should be noted that theminiaturized femtosecond laser system 10 may be a desktop system toallow treatment of the patient sitting in an upright position. Thiseliminates the need of certain optomechanic arm mechanisms, and greatlyreduces the complexity, size, and weight of the laser system.Alternatively, the miniaturized laser system may be designed as aconventional femtosecond laser system, where the patient is treatedwhile lying down.

FIG. 3 illustrates a simplified block diagram of an exemplary controller22 that may be used by the laser surgical system 10 according to anembodiment of this invention. Controller 22 typically includes at leastone processor 52 which may communicate with a number of peripheraldevices via a bus subsystem 54. These peripheral devices may include astorage subsystem 56, comprising a memory subsystem 58 and a filestorage subsystem 60, user interface input devices 62, user interfaceoutput devices 64, and a network interface subsystem 66. Networkinterface subsystem 66 provides an interface to outside networks 68and/or other devices. Network interface subsystem 66 includes one ormore interfaces known in the arts, such as LAN, WLAN, Bluetooth, otherwire and wireless interfaces, and so on.

User interface input devices 62 may include a keyboard, pointing devicessuch as a mouse, trackball, touch pad, or graphics tablet, a scanner,foot pedals, a joystick, a touch screen incorporated into a display,audio input devices such as voice recognition systems, microphones, andother types of input devices. In general, the term “input device” isintended to include a variety of conventional and proprietary devicesand ways to input information into controller 22.

User interface output devices 64 may include a display subsystem, aprinter, a fax machine, or non-visual displays such as audio outputdevices. The display subsystem may be a flat-panel device such as aliquid crystal display (LCD), a light emitting diode (LED) display, atouchscreen display, or the like. The display subsystem may also providea non-visual display such as via audio output devices. In general, theterm “output device” is intended to include a variety of conventionaland proprietary devices and ways to output information from controller22 to a user.

Storage subsystem 56 can store the basic programming and data constructsthat provide the functionality of the various embodiments of the presentinvention. For example, a database and modules implementing thefunctionality of the methods of the present invention, as describedherein, may be stored in storage subsystem 56. These software modulesare generally executed by processor 52. In a distributed environment,the software modules may be stored on a plurality of computer systemsand executed by processors of the plurality of computer systems. Storagesubsystem 56 typically comprises memory subsystem 58 and file storagesubsystem 60.

Memory subsystem 58 typically includes a number of memories including amain random access memory (RAM) 70 for storage of instructions and dataduring program execution and a read only memory (ROM) 72 in which fixedinstructions are stored. File storage subsystem 60 provides persistent(non-volatile) storage for program and data files. File storagesubsystem 60 may include a hard disk drive along with associatedremovable media, a Compact Disk (CD) drive, an optical drive, DVD,solid-state memory, and/or other removable media. One or more of thedrives may be located at remote locations on other connected computersat other sites coupled to controller 22. The modules implementing thefunctionality of the present invention may be stored by file storagesubsystem 60.

Bus subsystem 54 provides a mechanism for letting the various componentsand subsystems of controller 22 communicate with each other as intended.The various subsystems and components of controller 22 need not be atthe same physical location but may be distributed at various locationswithin a distributed network. Although bus subsystem 54 is shownschematically as a single bus, alternate embodiments of the bussubsystem may utilize multiple busses.

Due to the ever-changing nature of computers and networks, thedescription of controller 22 depicted in FIG. 3 is intended only as anexample for purposes of illustrating one embodiment of the presentinvention. Many other configurations of controller 22, having more orfewer components than those depicted in FIG. 3, are possible.

As should be understood by those of skill in the art, additionalcomponents and subsystems may be included with laser system 10. Forexample, spatial and/or temporal integrators may be included to controlthe distribution of energy within the laser beam, as described in U.S.Pat. No. 5,646,791, which is incorporated herein by reference. Ablationeffluent evacuators/filters, aspirators, and other ancillary componentsof the surgical laser system are known in the art, and may be includedin the system. In addition, an imaging device or system may be used toguide the laser beam. Further details of suitable components ofsubsystems that can be incorporated into an ophthalmic laser system forperforming the procedures described here can be found incommonly-assigned U.S. Pat. No. 4,665,913, U.S. Pat. No. 4,669,466, U.S.Pat. No. 4,732,148, U.S. Pat. No. 4,770,172, U.S. Pat. No. 4,773,414,U.S. Pat. No. 5,207,668, U.S. Pat. No. 5,108,388, U.S. Pat. No.5,219,343, U.S. Pat. No. 5,646,791, U.S. Pat. No. 5,163,934, U.S. Pat.No. 8,394,084, U.S. Pat. No. 8,403,921, U.S. Pat. No. 8,690,862, U.S.Pat. No. 8,709,001, U.S. application Ser. No. 12/987,069, filed Jan. 7,2011, and U.S. application Ser. No. 13/798,457 filed Mar. 13, 2013,which are incorporated herein by reference.

In an embodiment, the laser surgery system 10 includes a femtosecondoscillator-based laser operating in the MHz range, for example, 10 MHz,to perform three-dimensional tissue dissection, e.g., corneal flapcutting, during an ophthalmic procedure. For ophthalmic applications,the XY-scanner 28 may utilize a pair of scanning mirrors or other optics(not shown) to angularly deflect and scan the pulsed laser beam 18. Forexample, scanning mirrors driven by galvanometers may be employed, eachscanning the pulsed laser beam 18 along one of two orthogonal axes. Afocusing objective (not shown), whether one lens or several lenses,images the pulsed laser beam onto a focal plane of the laser surgerysystem 10. The focal point of the pulsed laser beam 18 may thus bescanned in two dimensions (e.g., the X-axis and the Y-axis) within thefocal plane of the laser surgery system 10. Scanning along a thirddimension, i.e., moving the focal plane along an optical axis (e.g., theZ-axis), may be achieved by moving the focusing objective, or one ormore lenses within the focusing objective, along the optical axis. It isnoted that in many embodiments, the XY-scanner 28 deflects the pulselaser beam 18 to form a scan line.

The laser surgery system 10 derives mathematic relations to performangled side cut (e.g., for a corneal flap cut), and other shaped sidecuts that can be realized by synchronizing the motions of the XY-scanner28 with the motion of the Z-scanner (e.g., fast-Z scanner) 20. In anembodiment, the controller 22 of the laser surgery system 10synchronizes an oscillation of the XY-scanner 28 and an oscillation ofthe Z-scanner 20. FIG. 4 illustrates a synchronization of the XY-scanner28 and the Z-scanner 20. While moving the XY-scanner 28 to perform a(e.g., circular) side cut 500, the radius of the circle is modulated insynchronization with the Z-scanner 20, so that various angled or shapedside cut cross-sections can be obtained. The radius of a side cut asdrawn by the XY-scanner 28 at time t, R(t), keeps a fixed relation withside cut depth Z(t), i.e., R=R(Z), where the function can take any formthat can form a dissection surface of revolution around the Z-axispassing through the center of the flap. This means that R is a functionof Z, i.e., for a given Z, there is only one value of R. Two exemplaryfunctions are:

R=R ₀ +a·Z,  equation (1),

for a linear side cut, and

R=R ₀ +a·Z ²,  equation (2),

for a parabolic side cut.

FIGS. 5A and 5B show exemplary cross-sections of side cuts,corresponding to equation (1) and equation (2), respectively. When theline 610 (FIG. 5A) or curve 620 (FIG. 5B) is rotated around the Z-axis,a surface of revolution will be formed. This surface will dissect thetissue within the volume of revolution (e.g., for a corneal flap) fromregion beyond the volume of revolution (e.g., the rest of the cornea).In general, when R(Z) is a function of Z (i.e., for any given Z, thereis a unique value of R), a side cut dissection surface can be formed byrotating the curve R(Z) around the Z-axis.

FIGS. 6A and 6B show exemplary cross-sections of side cuts when R(Z) isnot a single-valued function of Z. In general, the multi-branchedfunction R(Z) may be categorized into two types. In type 1, as shown inFIG. 6A, R(Z) contains closed loop(s). When the curve R(Z) is rotatedaround the Z-axis, the side cut will not just dissect but will alsoremove tissues in the volume marked by the encircled area 700 afterrevolution around the Z-axis. In type 2, as shown in FIG. 6B, R(Z) is amulti-branched function of Z, but does not contain closed loop. In thiscase, rotation of the R(Z) curve around the Z-axis will still form adissection surface without removing material.

In an embodiment, the laser surgery system 10 forms side cut shapeswhere R(Z) is a single-valued function of Z. In general, for any givenfunction of Z(t), a synchronized side cut can be formed with any givenfunction of R(Z). Using the format of Taylor series, we have

$\begin{matrix}{{{R(t)} = {{R\left\lbrack {Z(t)} \right\rbrack} = {\sum\limits_{n = 0}^{\infty}\; {c_{n} \cdot \left\lbrack {Z(t)} \right\rbrack^{n}}}}},,} & {{equation}\mspace{14mu} (3)}\end{matrix}$

where {n} is an integer and {c_(n)} are real number coefficients.Equation (3) is the general format for a synchronized side cut. {n}represents the shape of the cut. For example, when n is 1, thesynchronized side cut is linear. The function Z(t) can be any type,depending on the capability of the Z-scanner 20, e.g., a fast-Z scanner.In this embodiment, Z(t) is a sinusoidal function of time, i.e., it onlyoscillates at a single frequency.

FIGS. 7A to 7D show simulated examples using synchronization relationof:

$\begin{matrix}{\mspace{79mu} {{{Z(t)} = {A_{Z} \cdot {\sin \left( {2{\pi \cdot f_{Z} \cdot t}} \right)}}},}} & {{equation}\mspace{14mu} (4)} \\{{{X(t)} = {\left\lbrack {R_{0} + {A_{R} \cdot {\sin \left( {{2{\pi \cdot f_{R} \cdot t}} + \phi_{0}} \right)}}} \right\rbrack \cdot {\cos \left( {{\frac{V_{C}}{R_{0}} \cdot t} + \frac{\Theta}{2}} \right)}}},\mspace{20mu} {and},} & {{equation}\mspace{14mu} (5)} \\{{{{Y(t)} = {\left\lbrack {R_{0} + {A_{R} \cdot {\sin \left( {{2{\pi \cdot f_{R} \cdot t}} + \phi_{0}} \right)}}} \right\rbrack \cdot {\sin \left( {{\frac{V_{C}}{R_{0}} \cdot t} + \frac{\Theta}{2}} \right)}}},\mspace{20mu} {{where}\text{:}}\;,}\mspace{14mu}} & {{equation}\mspace{14mu} (6)}\end{matrix}$

X(t) X scanner position as function of timeY(t) Y scanner position as function of timeZ(t) focus position as function of timeA_(Z) Amplitude of Z(t) oscillation (2A_(Z) is equal to the totalcutting depth range)f_(Z) Fast-Z frequencyR₀ Central radius, around which the XY scanner oscillatef_(R) Radial oscillation frequencyA_(R) Amplitude of radial oscillationφ₀ Fixed phase difference between Z(t) and R(t)Θ Hinge width control parameter expressed in angle.

The simulations may be coded using programming language known in thearts, e.g., MATLAB. FIG. 7A shows a 70° side-cut with A_(Z)=80 μm,f_(Z)=20 Hz, A_(R)=f_(R)=20 Hz, φ₀=0°. FIG. 7B shows a parabolicside-cut with A_(Z)=80 μm, f_(Z)=20 Hz, A_(R)=f_(R)=40 Hz, φ₀=270°. FIG.7C shows a f_(R)=3f_(Z) synchronized side-cut with A_(Z)=80 μm, f_(Z)=20Hz, A_(R)=f_(R)=60 Hz, φ₀=180°. FIG. 7D shows a f_(R)=4f_(Z)synchronized side-cut with A_(Z)=80 μm, f_(Z)=20 Hz, A_(R)=f_(R)=80 Hz,φ₀=90°.

In an embodiment, the controller 22 maintains the synchronization forthe desired initial position and for the fixed relation among themotions of the XY-scanner 28 and the Z-scanner 20 during the entirecourse of the side cut procedure. In this embodiment, the laser surgerysystem 10 may establish close-loop feedback among X(t), Y(t), and Z(t)for every cycle of Z(t). In another embodiment, the controller 22maintains the synchronization for the desired initial position and forthe fixed relation among the motions of the XY-scanner 28 and theZ-scanner 20 during the entire course of the side cut procedure withoutfeedback. The laser surgery system 10 also performs error management inorder to maintain the synchronization.

In an embodiment, the Z-scanner 20,—e.g., fast-Z-scanner—, can be drivenby voice coil mechanism. In another embodiment, the Z-scanning can berealized by using various liquid lens technologies.

It is noted that the synchronized cuts described in the embodimentsherein can also be used for laser material processing and micromachiningfor other transparent materials.

FIG. 8 illustrates a process 800 of the laser surgery system 10according to an embodiment. The laser surgical system 10 starts thesurgical procedure with a predetermined three-dimensional cuttingpattern (Action Block 810). The pattern may be received using one ormore input devices 62. The pattern may be of any shape as describedabove. In an ophthalmic surgery procedure, the pattern may be a threedimensional angled tissue dissection without, e.g., an angled side cutof a corneal flap, or with, removal of the tissue. In othernon-ophthalmic procedures, the pattern may be a three dimensional angledtissue dissection without, or with, removal of the target material. Thelaser surgery system 10 generates the X(t), Y(t) and Z(t) trajectoriesof the XY-scanner 28 and Z-scanner 20, e.g., fast-Z scanner, as functionof time (Action Block 820). The trajectories may be generated using analgorithm as shown in Equation (1), (2), or (3) above. The XY-scanner 28and the Z-scanner 20 are thus synchronized in a fixed relation. Thelaser surgery system 10 controls the XY-scanner 28 and Z-scanner 20 tomove according X(t), Y(t) and Z(t) respectively (Action Block 830). Thelaser surgery system 10 then maintains the synchronization for thedesired initial position and for the fixed relation among the motions ofthe XY-scanner 28 and the Z-scanner 20 during the entire course of thecut procedure (Action Block 840). To maintain the synchronization, thelaser surgery system 10 may establish close-loop feedback among X(t),Y(t), and Z(t) for every cycle of Z(t).

All patents and patent applications cited herein are hereby incorporatedby reference in their entirety.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

While certain illustrated embodiments of this disclosure have been shownand described in an exemplary form with a certain degree ofparticularity, those skilled in the art will understand that theembodiments are provided by way of example only, and that variousvariations can be made without departing from the spirit or scope of theinvention. Thus, it is intended that this disclosure cover allmodifications, alternative constructions, changes, substitutions,variations, as well as the combinations and arrangements of parts,structures, and steps that come within the spirit and scope of theinvention as generally expressed by the following claims and theirequivalents.

What is claimed is:
 1. An ophthalmic surgical laser system comprising: alaser delivery system for delivering a pulsed laser beam to a target ina subject's eye; an XY-scan device to deflect the pulsed laser beam; aZ-scan device to modify a depth of a focus of the pulsed laser beam; anda controller configured to synchronize an oscillation of the XY-scandevice and an oscillation of the Z-scan device to form an angledthree-dimensional laser tissue dissection.
 2. The ophthalmic surgicallaser system of claim 1 further comprises a resonant scanner.
 3. Theophthalmic surgical laser system of claim 1, wherein the XY-scan devicedeflects the pulsed laser beam to form a scan line.
 4. The ophthalmicsurgical laser system of claim 1 further forms the angledthree-dimensional laser tissue dissection into any shape.
 5. Theophthalmic surgical laser system of claim 1, wherein the synchronizationof the XY-scan device and the Z-scan device has a fixed relation overtime.
 6. The ophthalmic surgical laser system of claim 1, wherein theangled three-dimensional laser tissue dissection is linear and isdetermined by R=R₀+a·Z where R is a central radius of the XY-scandevice, R₀ is the central radius of the XY-scan device at time 0, a is aconstant, and Z is a focus position of the Z-scan device.
 7. Theophthalmic surgical laser system of claim 1, wherein the angledthree-dimensional laser tissue dissection is parabolic and is determinedby R=R₀+a·Z² where R is a central radius of the XY-scan device, R₀ isthe central radius of the XY-scan device at time 0, a is a constant, andZ is a focus position of the Z-scan device.
 8. The ophthalmic surgicallaser system of claim 1, wherein the angled three-dimensional${R(t)} = {{R\left\lbrack {Z(t)} \right\rbrack} = {\sum\limits_{n = 0}^{\infty}\; {c_{n} \cdot \left\lbrack {Z(t)} \right\rbrack^{n}}}}$laser tissue dissection is a shape determined by where R(t) is a centralradius of the XY-scan device at time t, is Z(t) is a focus position ofthe Z-scan device at time t, c is a real number coefficient, and n is aninteger.
 9. The ophthalmic surgical laser system of claim 1, wherein thecontroller is further configured to perform error management and tomaintain the synchronization of the oscillation of the XY-scan deviceand the oscillation of the Z-device.
 10. The ophthalmic surgical lasersystem of claim 1, wherein the controller is furthered configured toremove tissue.
 11. A method for dissecting tissue of an eye using anophthalmic surgical laser system, the method comprises the steps of:generating a pulsed laser beam; delivering the pulsed laser beam to atarget in a subject's eye; deflecting, by an XY-scan device, the pulsedlaser beam; modifying, by a Z-scan device, a depth of a focus of thepulsed laser beam; and synchronizing, by a controller, an oscillation ofthe XY-scan device and an oscillation of the Z-scan device to form anangled three-dimensional laser tissue dissection.
 12. The method ofclaim 11 wherein the ophthalmic surgical laser system further comprisesa resonant scanner.
 13. The method of claim 11 wherein the XY-scandevice deflects the pulsed laser beam to form a scan line.
 14. Themethod of claim 11 further forms the angled three-dimensional lasertissue dissection into any shape.
 15. The method of claim 11 wherein thesynchronization of the XY-scan device and the Z-scan device has a fixedrelation over time.
 16. The method of claim 11 wherein the angledthree-dimensional laser tissue dissection is linear and is determined byR=R₀+a·Z where R is a central radius of the XY-scan device, R₀ is thecentral radius of the XY-scan device at time 0, a is a constant, and Zis a focus position of the Z-scan device.
 17. The method of claim 11wherein the angled three-dimensional laser tissue dissection isparabolic and is determined by R=R₀+a·Z² where R is a central radius ofthe XY-scan device, R₀ is the central radius of the XY-scan device attime 0, a is a constant, and Z is a focus position of the Z-scan device.18. The method of claim 11 wherein the angled three-dimensional lasertissue dissection is a shape determined by${R(t)} = {{R\left\lbrack {Z(t)} \right\rbrack} = {\sum\limits_{n = 0}^{\infty}\; {c_{n} \cdot \left\lbrack {Z(t)} \right\rbrack^{n}}}}$where R(t) is a central radius of the XY-scan device at time t, is Z(t)is a focus position of the Z-scan device at time t, c is a real numbercoefficient, and n is an integer.
 19. The method of claim 11 wherein thecontroller is further configured to perform error management and tomaintain the synchronization of the oscillation of the XY-scan deviceand the oscillation of the Z-device.
 20. An ophthalmic surgical lasersystem comprising: a laser delivery system for delivering a pulsed laserbeam to a target in a subject's eye; a resonant scanner; an XY-scandevice to deflect the pulsed laser beam to form one or more scan lines;a Z-scan device to modify a depth of a focus of the pulsed laser beam;and a controller configured to synchronize an oscillation of the XY-scandevice and an oscillation of the Z-scan device to form an angledthree-dimensional laser tissue dissection into any shape.